Conventionally, Ni-based alloys have been used as the base material for aircraft engine blades, but in recent years, the use of TiAl-based alloys, which exhibit high specific strength, has become possible.
However, as disclosed in Patent Citation 1, TiAl-based alloys exhibit poor formability, and are difficult to cut. Further, TiAl-based alloys are more brittle than Ni-based alloys, and tend to be prone to the generation of a work-affected layer on the worked surface when machining work such as cutting or grinding is performed.
A work-affected layer has increased hardness compared with the base material, and therefore the surface of a TiAl-based alloy with a work-affected layer formed thereon tends to be prone to cracking.